In typical heavy-duty vehicle applications, including those with hybrid drive systems, a rotating internal combustion engine includes multiple gear and/or pulley and belt power take-offs (PTOs) that operate the vehicle subsystems and accessories. As a result, turning off the engine causes the vehicle subsystems and accessories to be turned off.
It is desirable to eliminate engine idling at vehicle stops to, among other things, increase fuel economy, minimize noise, and minimize engine exhaust emissions pollution to improve the quality of the operating environment. This is especially true for transportation and delivery vehicles such as, but not limited to, urban transit buses and local package freight pick up and delivery vans that may experience hundreds of stops during daily operation.
A driver could manually turn off and turn on an engine when stopped; however, in addition to the problem of the vehicle subsystems and accessories not operating, a typical electric starter motor for the internal combustion engine would wear out rather quickly because it is typically not designed for the hundreds of stop-starts per day of transportation and delivery vehicles. Furthermore, stopping and restarting the engine rotation and associated PTO engine coolant and lubrication pumps could have an effect on engine wear and durability.